The present invention relates generally to a joint forming apparatus and more specifically to a die and punch and related method for forming a joint between sheets of material.
In the manufacture of products, there is often a need to join a pair or several pieces of material, such as sheet metal to build various assemblies and subassemblies. There are many different means for accomplishing this joining task. For example, there is adhesive bonding, welding or cold deformation. Both bonding and welding processes require the introduction of a foreign material to the assembly. The foreign material can tend to fail, thereby weakening the assembly. In cold deformation, several pieces of sheet material are plastically deformed in such a manner that they are locked together. Depending on the thickness, strength and/or the number of pieces of material to be joined, a great amount of force is required to accomplish this task.
Traditional presses for providing this force include in-line hydraulic presses and accordion-type toggle presses. Such presses, however, are often heavy and include many intricate parts making maintenance difficult and time consuming. Furthermore, many presses require a robot to feed (such as horizontally) the pieces of material into a position between a die and punch. Moreover, in many instances it can become difficult and inefficient to manage and accommodate the associated rotational and translational movements of the various components in the press.
In accordance with the present invention, a clamping apparatus is provided. The apparatus generally includes a clamp body, an arm, a punch, a die and a first linear actuator. The arm is rotatably fixed to the clamp body around a first pivot axis between a closed position and an open position. The punch is mounted to one of the body and the arm. The die is fixedly mounted to the other of the body and the arm. The first linear actuator includes a rod that is rotatably coupled to the arm around a second pivot axis. The rod moves between a first position corresponding to the arm being in the closed position and a second position corresponding to the arm being in the open position. A first distance is defined between the first and second pivot axes in the closed position. A second distance is defined between the first and second pivot axes in the open position. The first and second distances are equivalent.
According to additional features of the present invention, the first linear actuator is rotatably fixed to the body about a third pivot axis. The linear actuator rotates around the third pivot axis during translation of the rod between the first and second positions. The arm generally comprises an arcuate body having a first body portion that extends between a first end and the first pivot axis and a second body portion that extends between the second end and the first pivot axis. The first end of the first arm includes one of the punch and die. The second end of the arm includes an engagement member that is configured to contact a portion of the clamp body when the arm rotates to the closed position.
According to additional aspects of the present invention, a second linear actuator is provided on the clamp body. The second linear actuator includes a movable member that moves between a retracted position and an extended position. In the extended position, the movable member is aligned for contact with the second end of the arm and inhibits rotation of the arm around the first pivot axis toward the open position during operation of the punch.
A method for clinching a workpiece with a clamping apparatus is provided. The clamping apparatus is moved to an open position. The workpiece is located between a punch and die oppositely mounted to a clamp body and an arm, respectively, of the clamping apparatus. A rod of a first linear actuator is actuated from a first position to a second position. The arm is caused to rotate relative to the clamp body around a first pivot axis and into a closed position. The rod is rotatably coupled to the arm around a second pivot axis. A first distance is defined between a first and second pivot axes in the closed position and a second distance is defined between the first and second axes in the open position. The first and second distances are equivalent. The punch is then actuated.
According to other aspects of the present invention, the method further comprises contacting an engagement member disposed on the arm with a stop disposed on the clamp body upon rotation of the arm into the closed position. Actuating the rod further comprises rotating the first linear actuator relative to the body about a third pivot axis. According to other aspects of the present invention, the method further comprises actuating a second linear actuator from a first position to a second position causing a movable member to become aligned for contact with the arm prior to actuating the punch. The movable member engages and inhibits rotation of the arm around the first pivot axis toward the open position upon actuation of the punch.
According to other aspects of the present invention, the clamping apparatus is advantageous over conventional clamping devices. In this regard, the clamping apparatus according to the present invention provides a lower cost clamping configuration that requires less moving parts compared to other conventional clamping devices that may incorporate a camming action between a track and follower associated with the arm. Furthermore, the clamping apparatus of the present invention provides a swing arm that rotates around a pivot pin to an open position that allows vertical insertion of workpieces onto the die. The swing arm has a counterbalance body portion that extends opposite the pivot pin relative to the punch assembly to improve balance of the swing arm relative to the clamp body. The configuration of the swing arm, clamp body and first actuator provide an apparatus that accommodates higher loads and has improved balance as compared to conventional clamping devices.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.